Quadrupedal bounding with an actuated spinal joint

Abstract

Abstract-Most legged vertebrates use flexible spines and supporting muscles to provide auxiliary power and dexterity for dynamic behaviors, resulting in higher speeds and additional maneuverability during locomotion. However, most existing legged robots capable of dynamic locomotion incorporate only a single rigid trunk with actuation limited to legs and associated joints. In this paper, we investigate how quadrupedal bounding can be achieved in the presence of an actuated spinal joint and characterize associated performance improvements compared to bounding with a rigid robot body. In the context of both a new controller structure for bounding with a body joint and existing bounding controllers for the rigid trunk, we use optimization methods to identify the highest performance gait parameters and establish that the spinal joint allows increased forward speeds and hopping heights.

Core Actuation Promotes Self-manipulability on a Direct-Drive Quadrupedal Robot

“…Simulation studies of reduced-order models suggest that core actuation and compliance can provide increased speed, stability, and apex height while running [5,6,7]. Self-stabilizing gaits and decreased energetic cost of transport have been found with purely passive core compliance [8].…”

“…Simplified models of quadrupedal platforms, such as the one depicted in Figure 1(a), often take the form of three-degree-of-freedom rigid bodies with common distances between the hips and mass center [16,17] and assume massless legs able to apply wrenches on the mass center when in contact with the ground subject to friction cone constraints. Following [6,7,8,9], we add core actuation to this model by introducing an actuated revolute joint to the body, depicted in Figure 1(b) (note that alternative formulations exist, such as [5]). Here we make the simplifying assumption that the parameters of each body segment are equal and that the mass center of each body segment is aligned with the leg hip, as is approximately true for the machine presented in Section 3.…”

Empirical validation of a spined sagittal-plane quadrupedal model

“…Following [11], [12], [13], [15], [18], we propose a reduced-order sagittal-plane spined quadrupedal model consisting of two bipedal body segments connected by a massless pin joint 3 as shown in Figure 1. We take the state of the model to be given by q = (x, z, φ, ψ)…”

“…An array of simulation studies of steady-state robotic quadrupedal running utilizing core actuation and compliance has generated a class of reduced-order models that suggest speed and stability benefits [10], [11], [12], [13], yet verifying these models on power-autonomous physical machines remains open. Progress towards this goal was made by the servo-driven Bobcat robot utilizing off-board power [14].…”

Influence of trunk structure on posture transition from quadrupedalism to bipedalism

“…For a simple posture transition from quadrupedalism to bipedalism, an animal-like trunk mechanism with viscoelastic joints is adopted. Although some studies have examined the effect of a trunk mechanism with viscoelastic joints on quadrupedalism [12][13][14] and bipedalism [15], they do not discuss about the effect on the transition. Therefore, in this study, we designed a model that adopts the animal-like trunk mechanism in a simulation and observed the effect on the transition from posture of quadrupedalism to that of bipedalism.…”